DynaTags

Instances of this class are passed to the Filter constructor to
support running selected suites and tests via dynamic tagging. For example, dynamic tags can be used
to rerun tests that failed previously, or tests selected via a wildcard from Runner or
the Scala interpreter.

suiteTags

a map from String suite ID to a set of tags for that suite.

testTags

a map from String suite ID to a map, whose keys are test names and values the tags for that test.